1. Field of the Invention
The invention relates to a bicycle wheel rim, more particularly to a bicycle wheel rim capable of mounting selectively with a circular disc and a set of spokes.
2. Description of the Related Art
As shown in FIGS. 1 and 2, a conventional bicycle wheel rim 1 includes spaced-apart left and right annular tire retaining walls 12 and an annular spoke mounting wall 11 interconnecting the tire retaining walls 12. The spoke mounting wall 11 is formed with a plurality of angularly displaced spoke mounting holes 15 which are arranged along length of the spoke mounting wall 11 for retaining spoke fasteners 14 therein. The tire retaining walls 12 and the spoke mounting wall 11 cooperatively confine a tire retaining space 2 for retaining a bicycle tire 20 therein.
The bicycle tire 20 typically includes an inflatable inner tire body 21 and an outer tire body 22 enclosing the inner tire body 21, as shown in FIGS. 2 and 3. During the installation of the bicycle tire 20, the inner tire body 21 is first sleeved on the wheel rim 1 before inflation. The inner tire body 21 is usually disposed deeply in the tire retaining space 2 and close to the spoke mounting wall 11, and cannot be easily gripped when the outer tire body 22 is to be subsequently installed on the wheel rim 1.
Recently, it has been suggested in the art that the spokes be replaced with a circular disc made of aluminum-magnesium alloy. However, the circular disc can only be mounted on a rim body which is specially designed and which is provided with means for mounting the circular disc. It is desirable to provide a bicycle wheel rim which can be mounted with the aforesaid circular disc and which can be alternatively mounted with a set of spokes.
Therefore, the main object of the present invention is to provide a bicycle wheel rim capable of mounting selectively with a circular disc and a set of spokes.
Accordingly, the bicycle wheel rim of the present invention includes an integrally formed annular rim body with a central axis. The rim body has annular left and right tire retaining walls, and an annular base wall interconnecting the tire retaining walls. The tire retaining walls are spaced apart from each other. Each of the tire retaining walls has a radial inner edge proximate to the central axis of the rim body, a radial outer edge distal to the central axis of the rim body, and an intermediate portion between the radial inner and radial outer edges. The annular base wall has a radial inner face facing the central axis, a radial outer face opposite to the radial inner face, a left section which has a left terminating edge connected to the radial inner edge of the left tire retaining wall and a right terminating edge, a right section which has a right terminating edge connected to the radial inner edge of the right tire retaining wall and a left terminating edge, and a vaulted portion interconnecting the right terminating edge of the left section and the left terminating edge of the right section. The vaulted portion is vaulted in a radial outward direction relative to the left and right sections so as to define an annular recess in the radial inner face and an annular protrusion on the radial outer face. The annular recess is adapted for retaining a peripheral portion of a circular disc therein. Optionally, the base wall is formed with a plurality of spoke mounting holes which are distributed in the left and right sections and which are adapted for retaining spoke fasteners therein.